title: Comparison of two commercial molecular tests for the detection of Clostridium difficile in the routine diagnostic laboratory.
abstract: Two commercial real-time PCR assays for the detection of Clostridium difficile, BD GeneOhm Cdiff assay (BD Diagnostics) and Xpert C. difficile assay (Cepheid), were compared to each other and to toxigenic culture, which was used as a gold standard, on a set of 194 clinical stools submitted for routine diagnostic analysis. Of 28 (14.4 %) toxigenic culture positive samples 23 were positive with both assays, the BD and the Cepheid real-time PCR assays, 4 were positive only by Cepheid Xpert C. difficile assay and 1 sample was negative by both PCR assays, resulting in sensitivity, specificity, positive predictive value and negative predictive value of 82.1, 98.2, 88.5 and 97.0 %, respectively, for the BD GeneOhm Cdiff assay, and 96.4, 97.3, 87.1 and 99.3 %, respectively, for the Cepheid Xpert C. difficile assay. Altogether 26 out of 194 (13.4 %) samples were reported invalid by Cepheid. Toxigenic C. difficile positive samples contained 15 different PCR ribotypes distributed into toxinotype 0 and 2 different variant toxinotypes (III, IV). Clinical data were available for 24 out of 28 (85.7  %) toxigenic C. difficile positive patients and 18 (75.0 %) of them were diagnosed with diarrhoea, while others had other symptoms or risk factors related to possible C. difficile infection (antibiotics, bloody stool, peritonitis, Crohn's disease).
authors.affiliation: Institute of Public Health Maribor, Maribor, Slovenia.
authors.forename: Valerija
authors.initials: V
authors.lastname: Zidarič
authors.affiliation: Department of Infectious Diseases, University Medical Center Maribor, Ljubljanska ulica 5, 2000 Maribor, Slovenia.
authors.forename: Bozena
authors.initials: B
authors.lastname: Kotnik Kevorkijan
authors.affiliation: Institute of Public Health Maribor, Maribor, Slovenia.
authors.forename: Nadja
authors.initials: N
authors.lastname: Oresic
authors.affiliation: Institute of Public Health Maribor, Maribor, Slovenia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Janezic
authors.affiliation: Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CIPKEBIP), Ljubljana, Slovenia.|Faculty of Medicine, University of Maribor, Maribor, Slovenia.|Institute of Public Health Maribor, Maribor, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Rupnik
mesh_terms: D016360:Clostridioides difficile / Q000302:isolation & purification*; D003015:Clostridium Infections / Q000175:diagnosis* / Q000382:microbiology; D046508:Culture Techniques; D005243:Feces / Q000382:microbiology; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*